/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.xerces.internal.dom;

import org.w3c.dom.DocumentFragment;
import org.w3c.dom.Node;
import org.w3c.dom.Text;

/**
 * DocumentFragment is a "lightweight" or "minimal" Document
 * object. It is very common to want to be able to extract a portion
 * of a document's tree or to create a new fragment of a
 * document. Imagine implementing a user command like cut or
 * rearranging a document by moving fragments around. It is desirable
 * to have an object which can hold such fragments and it is quite
 * natural to use a Node for this purpose. While it is true that a
 * Document object could fulfil this role, a Document object can
 * potentially be a heavyweight object, depending on the underlying
 * implementation... and in DOM Level 1, nodes aren't allowed to cross
 * Document boundaries anyway. What is really needed for this is a
 * very lightweight object.  DocumentFragment is such an object.
 * <P>
 * Furthermore, various operations -- such as inserting nodes as
 * children of another Node -- may take DocumentFragment objects as
 * arguments; this results in all the child nodes of the
 * DocumentFragment being moved to the child list of this node.
 * <P>
 * The children of a DocumentFragment node are zero or more nodes
 * representing the tops of any sub-trees defining the structure of
 * the document.  DocumentFragment do not need to be well-formed XML
 * documents (although they do need to follow the rules imposed upon
 * well-formed XML parsed entities, which can have multiple top
 * nodes). For example, a DocumentFragment might have only one child
 * and that child node could be a Text node. Such a structure model
 * represents neither an HTML document nor a well-formed XML document.
 * <P>
 * When a DocumentFragment is inserted into a Document (or indeed any
 * other Node that may take children) the children of the
 * DocumentFragment and not the DocumentFragment itself are inserted
 * into the Node. This makes the DocumentFragment very useful when the
 * user wishes to create nodes that are siblings; the DocumentFragment
 * acts as the parent of these nodes so that the user can use the
 * standard methods from the Node interface, such as insertBefore()
 * and appendChild().
 *
 * @xerces.internal
 * @since PR-DOM-Level-1-19980818.
 */
public class DocumentFragmentImpl
    extends ParentNode
    implements DocumentFragment {

  //
  // Constants
  //

  /**
   * Serialization version.
   */
  static final long serialVersionUID = -7596449967279236746L;

  //
  // Constructors
  //

  /**
   * Factory constructor.
   */
  public DocumentFragmentImpl(CoreDocumentImpl ownerDoc) {
    super(ownerDoc);
  }

  /**
   * Constructor for serialization.
   */
  public DocumentFragmentImpl() {
  }

  //
  // Node methods
  //

  /**
   * A short integer indicating what type of node this is. The named
   * constants for this value are defined in the org.w3c.dom.Node interface.
   */
  public short getNodeType() {
    return Node.DOCUMENT_FRAGMENT_NODE;
  }

  /**
   * Returns the node name.
   */
  public String getNodeName() {
    return "#document-fragment";
  }

  /**
   * Override default behavior to call normalize() on this Node's
   * children. It is up to implementors or Node to override normalize()
   * to take action.
   */
  public void normalize() {
    // No need to normalize if already normalized.
    if (isNormalized()) {
      return;
    }
    if (needsSyncChildren()) {
      synchronizeChildren();
    }
    ChildNode kid, next;

    for (kid = firstChild; kid != null; kid = next) {
      next = kid.nextSibling;

      // If kid is a text node, we need to check for one of two
      // conditions:
      //   1) There is an adjacent text node
      //   2) There is no adjacent text node, but kid is
      //      an empty text node.
      if (kid.getNodeType() == Node.TEXT_NODE) {
        // If an adjacent text node, merge it with kid
        if (next != null && next.getNodeType() == Node.TEXT_NODE) {
          ((Text) kid).appendData(next.getNodeValue());
          removeChild(next);
          next = kid; // Don't advance; there might be another.
        } else {
          // If kid is empty, remove it
          if (kid.getNodeValue() == null || kid.getNodeValue().length() == 0) {
            removeChild(kid);
          }
        }
      }

      kid.normalize();
    }

    isNormalized(true);
  }

} // class DocumentFragmentImpl
